紧急求助！！！！{}中的有什么用

const     
  data:array [0..3] of 0..9=(8,4,2,6);     
var     
  i,ans,a,b,c,n,f:longint;     
begin    
  readln(n);    
  b:=1;   a:=n div 10;      b:=a mod 4;     
{if a<=100 then b:=data[b-1];    
  if a>=1000000 then b:=data[b-2];    
if (a>100) and (a<1000000) then } b:=data[b];     
  c:=n mod 10;        f:=1;     
  for i:=1 to c do f:=f*i;     
  f:=f*b;     
  while f mod 10=0 do f:=f div 10;     
  ans:=f mod 10;     
  write(ans);     
end.